External world skepticism is divided into two parts: the question of how one can certain of the existence of the world, and how we are to understand its nature, given that it is external to us and, therefore, "other." If we are unable to know a thing apart from ourselves, as many philosophers argue, the issue of knowing and knowing about the external world requires a mode of enquiry to get at its essence and consequences. Most philosophers divide the world into mental (thought, imagination, immeasurable objects) and extendable (shape, color, measurable) objects; skepticism seeks to analyze causality and relations between the two, as well as the possibility of their coexistence.
René Descartes, George Berkeley and David Hume offer various differing modalities that may be employed to investigate the external world. René Descartes' approach to external world skepticism concerns a universal doubt pertaining to our opinions and beliefs (and the foundations of each) as well as our senses, which may deceive us and, therefore, misinform our knowledge of the world. This absolute doubt is not applied to every particular, but rather to foundational beliefs that may lead to the undoing of entire areas of belief. In this view, cautions must be taken not just with regards to entire falsities, but also to partial truths, as these may also lead to deception.
George Berkeley argues that reason and argument from abstraction allows for a knowable external world. The soul is distinct from ideas, and so is able to bring the idea into existence by perceiving it. A thing is determined not to exist only on the grounds that it is perceived neither by an individual's mind nor the mind of any other created spirit; however, arguing from abstraction allows an object to exist without the primary perceiver. For example, one could perceive of a tree without also having to perceive of its leaves; as long as the abstraction takes place within "real existence", abstraction allows for reason to extend to the knowledge of the external world. We do not absolutely need an external world, only the idea and experience.
David Hume finds significant fault with both Descartes' and Berkeley's models. Descartes, he submits, is correct in critiquing the strength of the senses, but argues that there are more significant problems regarding the discrediting of the external world as a whole (An Enquiry Concerning Human Understanding, Section XII, Part I). Hume responds to Berkeley's statements by arguing that human presence "does not bestow being on [an external object]" (An Enquiry Concerning Human Understanding, Section XII, Part I). Hume rejects Berkeley's "perception by spirit" model by arguing that "an extension, that is neither tangible nor visible, cannot possibly be conceived," (An Enquiry Concerning Human Understanding, Section XII, Part I) although this would be possible if the soul was the only perceptive vehicle.
External World Skepticism:
Descartes
(31 March 1596 - 11 February 1650)
Purpose
Descartes' skepticism, or Cartesian skepticism, uses arguments against the possibility of an external world in a novel way: to ascertain certitude. The following is one way to construe this skeptical method, or Method of Doubt:
True ideas must be built on a foundation of certainty
Any ideas or assumptions which can be doubted are not certain
So, all knowledge must be doubted until a basic principle of certainty can be achieved
It is often argued that Descartes' motivation for this method was to undermine the Aristotelian physics he learned in high school. However, given the extreme nature of his arguments, going beyond attacks on the general ideas of physics: objects, space, and time, to doubting the very possibility of all existence, even his own. Descartes' doubts this because of the deception of his senses. In Meditation 1 He states "It is a mark of prudence never to place our complete trust in those who have deceived us even once." If we believe what we no not for certain than we would be foolish. Descartes' was trying to open up this line of thought. Thus, it is reasonable to conclude that Descartes' primary motivation was to reconstitute all philosophical thought about existence and being--about metaphysics. Thomas Reid, in An Inquiry into the Human Mind on the Principles of Common Sense, characterizes the Cartesian principle as follows:
The Cartesian...thinks that the existence of the body or of any of its qualities is not to be taken as a first principle; and that we ought to admit nothing concerning it but what by just reasoning can be deduced from our sensations, and he knows that by reflection we can form clear and distinct notions of our sensations without borrowing our notions of them by analogy from the objects of sense.
William Molyneux, who first translated Descartes' Meditations into English, understood the radical nature of Descartes thought compared it to that of The Creator himself:
[N]ext to the creation of all things out of nothing, the restoration of truth out of errors is the most Divine work; so that (with reverence be it spoken) the Incomparable Descartes does hereby deserve the name of a Creator. In the first meditation we are presented with a rude and indigested chaos of errors and doubt, till the Divine spirit of the Noble Descartes moves upon the confused face of these waters, and thereout produces some clear and distinct light. Till at last by a six days labor he establishes this fair fabric of the intellectual world on foundations that shall never be shaken. (Preface, 1645)
Descartes' true purpose of these argument is to substantiate two (or three) certainties:
The existence of himself as a thinking thing,
The existence of matter as extended thing,
[the existence of God]
Arguments
Descartes' skeptical arguments progress as a systematic attack on beliefs about:
Particulars
Universals
Being
His first argument, the deceiving senses argument attacks knowledge of object particulars, like the computer screen before your eyes:
All beliefs about particular external objects are derived from the senses.
All the senses have at one point deceived the mind, proving to give falsities as fact.
Therefore, any/all beliefs about particular external objects may be false.
Descartes' second argument, the dreaming argument, attacks knowledge of general ideas, like the idea of computers and whether it refers to an actually existing set of objects:
The objects of thought in dreams are representative of true things.
There is no way to distinguish sleeping from being awake.
Therefore, there are general true and existing things which may be represented in a sleep-consciousness.
The final argument of Descartes' , the evil demon argument, attacks knowledge of existence, Descartes' own existence:
All existing things are determined by a Superior Being.
However, the Superior Being may be a deceiver.
So, all beliefs about existing things may be false.
Descartes states in his final paragraph in Meditation One: "I will remain resolute and steadfast in this meditation, and even if it is not within my power to know anything true, it certainly is within my power to take care resolutely to withhold my assent to what is false." Descartes has attacked and stated that everything that he believes might not be real, and that we might all be under the spell of a Deceiver. Even though he is determined to not let this demon get the better of him, Descartes admits that subconsciously he wants to believe that he does exist, and wants to live his life as if he did exist. He states that he fears 'waking up' and possibly acknowledging that everything he knows might not exist.
=
=
External World Skepticism: Berkeley
(12 March 1685 – 14 January 1753)
Purpose
Berkeley's Skepticism comes in response to what he perceived as the greatest threat to Theism: "Materialism" or Corpuscularianism, a mechanistic account of reality that asserts an underlying imperceivable physical substrate in an abstract container of space that together produces perceivable qualities of color, heat, etc. in the minds of man. He is disagreeing with Indirect Realism, the belief that there is an external world in which we get our idea world from. This threat is founded on abstracting general physical principles or laws indirectly from experienced particulars. Hence, the thrust of Berkeley's attack is on the veracity of "abstraction." In its place is Berkeley's infamous principle: Esse est percipi(to be is to be perceived). (Principles, Part 1, 3) It is these mutually exclusive doctrines: abstraction and esse est percipi that the focus of Berkeley's attack on Corpuscularianism and form is Theistic apology.
Arguments
Berkely strives to prove that there is no physical world, there is only the mind. The basis of Esse est percipi is the following argument. (Principles, Part 1, 4) :
Existing objects are known by perception alone.
To perceive is to experience an object directly.
Therefore, only objects experienced directly exist.
So Berkely argues that we can only experience the world through the mind, and only objects that we perceieve actually exist. An important key to understanding the above argument is the realization of the relationship between the object and the sensation. Berkley holds that the object and the sensation are one in the same, and therefore we cannot separate the two. (Principles, Part 1, 5)
The Percipi argument forms the basis for Berkeley's skeptical argument against the external world (and hence Corpuscularianism). I will quote his argument directly:
[L]et it be considered the sensible qualities are color, figure, motion, smell, taste, and qualities of a similar kind--that is, the ideas perceived by sense. Now for an idea to exist in an unperceiving thing is a manifest contradiction, for to have an idea is all one as to perceive; that, therefore, in which color figure, and the like qualities exist must perceive them; hence it is clear there can be no unthinking substance of substratum of those ideas. (Principles, Part 1, 7)
[This argument can be formulated in the following way:
An idea is perceived by one or more sense(s).
We are only able to conceive of likenesses between preexisting ideas--color like another color, shape like another shape.
There is no unthinking substance which can perceive of either an idea or a relation between ideas.
The spirit is that substance which perceives.
Another argument for the same conclusion may be called the "Inconceivability" argument (Principles, Part 1, 22-3):
If one tries to argue that an object exists because he can imagine that it is possible for an object to exist without a perceiving mind, he can only come up with this idea using his senses.
Since all of our senses are deceptive, what he strives to prove is a contradiction because he is still using his faulty senses to prove his point.
So this argumnet does not suffice to prove that obects can exist without a perceiving mind.
Berkeley's argument undercuts the possibility of a "substance" which undergirds all properties. All that exists are these perceived properities, which are themselves ideas in the mind. Space beyond or outside of our spirits (that substance which perceives) is only an imagining of the mind. Hence, the Percipi argument provides the basis for Berkeley's Idealism, the claim that all reality merely consists of non-material ideas and the minds by which these ideas are brought into existence.
External World Skepticism:Hume
(7 May 1711 – 25 August 1776)
Purpose
Hume's Skepticism, or Mitigated skepticism, suspends judgment on all beliefs that are not "matters of fact", or practical matters of life. Hume is careful to distinguish use of skepticism from the following:
Excessive Skepticism (Pyrrhonian): Suspending judgment about all belief.
Affirming Skepticism (Cartesian): Suspending judgment of most belief to affirm a few metaphysical beliefs.
Doubting Skeptism: Long-standing suspending judgment about certainty of belief.
Arguments
The basis of Mitigated skepticism is Hume's argumentative affirmation of what is historically called The Theory of Ideas (TOI):
All experience is of properties dependent on the mind (i.e. secondary qualities).
Secondary qualities are ideas in the mind.
So, all experience is of ideas in the mind (rather than external objects). (TOI)
Skepticism is the best antidote to the predicament of the limitations of our experience. But the radical forms that have been historically useful are found wanting in practice. Thus, Hume prescribes Mitigated Skepticism, "which may be both durable and useful." (Enquiry XII, Part III) His argument may be stated as follows:
Our experience and reasoning are faulty regarding metaphysical and physical speculations (like space and time).
Thus, we must suspend judgment of belief regarding such speculations.
However, our experience and reason is reliable enough for matters of fact.
So, we must narrow all speculations to matters of fact.
Hume includes only two categories as "matters of fact": "abstract reasoning concerning quantity and number" such as how to measure the hypotenuse of a triangle as equal to the two other sides squared (such as the 3-4-5 method in carpentry) and "experimental reasoning concerning matter of fact and existence" such as the possible existence of finding a unicorn in one's travels. All else, "can contain nothing but sophistry and illusion." (Enquiry XII, Part III)
External World Skepticism
External world skepticism is divided into two parts: the question of how one can certain of the existence of the world, and how we are to understand its nature, given that it is external to us and, therefore, "other." If we are unable to know a thing apart from ourselves, as many philosophers argue, the issue of knowing and knowing about the external world requires a mode of enquiry to get at its essence and consequences. Most philosophers divide the world into mental (thought, imagination, immeasurable objects) and extendable (shape, color, measurable) objects; skepticism seeks to analyze causality and relations between the two, as well as the possibility of their coexistence.
René Descartes, George Berkeley and David Hume offer various differing modalities that may be employed to investigate the external world. René Descartes' approach to external world skepticism concerns a universal doubt pertaining to our opinions and beliefs (and the foundations of each) as well as our senses, which may deceive us and, therefore, misinform our knowledge of the world. This absolute doubt is not applied to every particular, but rather to foundational beliefs that may lead to the undoing of entire areas of belief. In this view, cautions must be taken not just with regards to entire falsities, but also to partial truths, as these may also lead to deception.
George Berkeley argues that reason and argument from abstraction allows for a knowable external world. The soul is distinct from ideas, and so is able to bring the idea into existence by perceiving it. A thing is determined not to exist only on the grounds that it is perceived neither by an individual's mind nor the mind of any other created spirit; however, arguing from abstraction allows an object to exist without the primary perceiver. For example, one could perceive of a tree without also having to perceive of its leaves; as long as the abstraction takes place within "real existence", abstraction allows for reason to extend to the knowledge of the external world. We do not absolutely need an external world, only the idea and experience.
David Hume finds significant fault with both Descartes' and Berkeley's models. Descartes, he submits, is correct in critiquing the strength of the senses, but argues that there are more significant problems regarding the discrediting of the external world as a whole (An Enquiry Concerning Human Understanding, Section XII, Part I). Hume responds to Berkeley's statements by arguing that human presence "does not bestow being on [an external object]" (An Enquiry Concerning Human Understanding, Section XII, Part I). Hume rejects Berkeley's "perception by spirit" model by arguing that "an extension, that is neither tangible nor visible, cannot possibly be conceived," (An Enquiry Concerning Human Understanding, Section XII, Part I) although this would be possible if the soul was the only perceptive vehicle.
External World Skepticism:
Descartes
(31 March 1596 - 11 February 1650)
Purpose
Descartes' skepticism, or Cartesian skepticism, uses arguments against the possibility of an external world in a novel way: to ascertain certitude. The following is one way to construe this skeptical method, or Method of Doubt:It is often argued that Descartes' motivation for this method was to undermine the Aristotelian physics he learned in high school. However, given the extreme nature of his arguments, going beyond attacks on the general ideas of physics: objects, space, and time, to doubting the very possibility of all existence, even his own. Descartes' doubts this because of the deception of his senses. In Meditation 1 He states "It is a mark of prudence never to place our complete trust in those who have deceived us even once." If we believe what we no not for certain than we would be foolish. Descartes' was trying to open up this line of thought. Thus, it is reasonable to conclude that Descartes' primary motivation was to reconstitute all philosophical thought about existence and being--about metaphysics. Thomas Reid, in An Inquiry into the Human Mind on the Principles of Common Sense, characterizes the Cartesian principle as follows:
The Cartesian...thinks that the existence of the body or of any of its qualities is not to be taken as a first principle; and that we ought to admit nothing concerning it but what by just reasoning can be deduced from our sensations, and he knows that by reflection we can form clear and distinct notions of our sensations without borrowing our notions of them by analogy from the objects of sense.
William Molyneux, who first translated Descartes' Meditations into English, understood the radical nature of Descartes thought compared it to that of The Creator himself:
[N]ext to the creation of all things out of nothing, the restoration of truth out of errors is the most Divine work; so that (with reverence be it spoken) the Incomparable Descartes does hereby deserve the name of a Creator. In the first meditation we are presented with a rude and indigested chaos of errors and doubt, till the Divine spirit of the Noble Descartes moves upon the confused face of these waters, and thereout produces some clear and distinct light. Till at last by a six days labor he establishes this fair fabric of the intellectual world on foundations that shall never be shaken. (Preface, 1645)
Descartes' true purpose of these argument is to substantiate two (or three) certainties:
Arguments
Descartes' skeptical arguments progress as a systematic attack on beliefs about:His first argument, the deceiving senses argument attacks knowledge of object particulars, like the computer screen before your eyes:
Descartes' second argument, the dreaming argument, attacks knowledge of general ideas, like the idea of computers and whether it refers to an actually existing set of objects:
The final argument of Descartes' , the evil demon argument, attacks knowledge of existence, Descartes' own existence:
Descartes states in his final paragraph in Meditation One: "I will remain resolute and steadfast in this meditation, and even if it is not within my power to know anything true, it certainly is within my power to take care resolutely to withhold my assent to what is false." Descartes has attacked and stated that everything that he believes might not be real, and that we might all be under the spell of a Deceiver. Even though he is determined to not let this demon get the better of him, Descartes admits that subconsciously he wants to believe that he does exist, and wants to live his life as if he did exist. He states that he fears 'waking up' and possibly acknowledging that everything he knows might not exist.
=
=
External World Skepticism: Berkeley
(12 March 1685 – 14 January 1753)
Purpose
Berkeley's Skepticism comes in response to what he perceived as the greatest threat to Theism: "Materialism" or Corpuscularianism, a mechanistic account of reality that asserts an underlying imperceivable physical substrate in an abstract container of space that together produces perceivable qualities of color, heat, etc. in the minds of man. He is disagreeing with Indirect Realism, the belief that there is an external world in which we get our idea world from. This threat is founded on abstracting general physical principles or laws indirectly from experienced particulars. Hence, the thrust of Berkeley's attack is on the veracity of "abstraction." In its place is Berkeley's infamous principle: Esse est percipi (to be is to be perceived). (Principles, Part 1, 3) It is these mutually exclusive doctrines: abstraction and esse est percipi that the focus of Berkeley's attack on Corpuscularianism and form is Theistic apology.Arguments
Berkely strives to prove that there is no physical world, there is only the mind. The basis of Esse est percipi is the following argument.(Principles, Part 1, 4)
:
So Berkely argues that we can only experience the world through the mind, and only objects that we perceieve actually exist. An important key to understanding the above argument is the realization of the relationship between the object and the sensation. Berkley holds that the object and the sensation are one in the same, and therefore we cannot separate the two. (Principles, Part 1, 5)
The Percipi argument forms the basis for Berkeley's skeptical argument against the external world (and hence Corpuscularianism). I will quote his argument directly:
[This argument can be formulated in the following way:
Another argument for the same conclusion may be called the "Inconceivability" argument (Principles, Part 1, 22-3):
Berkeley's argument undercuts the possibility of a "substance" which undergirds all properties. All that exists are these perceived properities, which are themselves ideas in the mind. Space beyond or outside of our spirits (that substance which perceives) is only an imagining of the mind. Hence, the Percipi argument provides the basis for Berkeley's Idealism, the claim that all reality merely consists of non-material ideas and the minds by which these ideas are brought into existence.
External World Skepticism:Hume
(7 May 1711 – 25 August 1776)
Purpose
Hume's Skepticism, or Mitigated skepticism, suspends judgment on all beliefs that are not "matters of fact", or practical matters of life. Hume is careful to distinguish use of skepticism from the following:Arguments
The basis of Mitigated skepticism is Hume's argumentative affirmation of what is historically called The Theory of Ideas (TOI):Skepticism is the best antidote to the predicament of the limitations of our experience. But the radical forms that have been historically useful are found wanting in practice. Thus, Hume prescribes Mitigated Skepticism, "which may be both durable and useful." (Enquiry XII, Part III) His argument may be stated as follows:
Hume includes only two categories as "matters of fact": "abstract reasoning concerning quantity and number" such as how to measure the hypotenuse of a triangle as equal to the two other sides squared (such as the 3-4-5 method in carpentry) and "experimental reasoning concerning matter of fact and existence" such as the possible existence of finding a unicorn in one's travels. All else, "can contain nothing but sophistry and illusion." (Enquiry XII, Part III)
Bibliography